Evaporator



Nov. 24, 1942; H. M. GRAHAM EVAPORATOR 'Fild Dec. 7. 1940 3' Sheets-Sheet 1' IN VENTOR Harald/116m :mmn nnulllll] A ITO/2% Nov, 24, 1942; H. GRAHAM 2,302,993

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Nov. 24, 1942. H. M.- GRAHAM EVAPORATOR Filed Dec. 7. 1940 3 Sheets-Shoot 3 'INVENTOR' 1 I flarolaZMGmhm ATTORNE Patented Nov. 24, 1942 EVAPORATOR Harold M. Graham, Bronxville, N. Y., assignor to The Lummus Company, New York, N. Y., a corporation Delaware Application December 7, 1940, Serial, No. 368,981

Claims. (Cl; 122-34) ber l2, a steam drying section l3, and the steam evaporators. reservoir l4. Except for the baflles, these re- In the evaporation of water for the purpose of spective chambers are all continuous and form generating steam, it is common to treat the water the interior of the evaporator I0.

For convenience, the evaporator may also be to reduce its hardness and the water used may 0 also contain some sediment in the form of solid considered to include a water chamber l5 below matter, which, together with the treating material, must be eliminated in order to produce the desired pure steam required in present day ceive the water which is to be evaporated into high pressure steam power practice. steam from the water inlet l6 by means to be A general object of my invention is to provide hereinafter described. an improved evaporating apparatus for the pro- Preferably, the water in the water chamber duction of relatively pure steam for boiler feed is evaporated by heat exchange with a heating water in which sludge, sediment, and other solid fluid which passes through tubular heat exchange matter are continuously knocked out of the steam 15 bundle generally indicated at l8, which may have by incoming feed water with the solids accu- *a suitable fixed tube sheet l9 and the channel mulating in the evaporating region, from which 20, into which the heating fluid is introduced they may be blown down as necessary. through the nozzle 2| and discharged through A further object of the invention is to prothe nozzle-22. As will be noted, the relative vide an improved unit evaporator for the prodiameter of the heat exchange tube sheet is, with duction of high purity steam, in the lower part respect to the required diameter of the evaporator of which is an evaporating coil submerged by H), makes it desirable to provide 'a conical shell a water bath and in the upper part of which are for the chamber II, which is the principal steam spaced steam generating, steam scrubbing, and evaporating chamber. This is in the interest of steam drying sections with a flow of steam from economy and permits the appropriate location of section to section, by which impurities and moisthe tube bundle I8 at the bottom of the evapoture are removed. rator l0 where it is submerged by the water in Still further objects of my invention will apthe water chamber l5. Furthermore, it aids the pear from the following description of a prenatural movement of steam toward the reservoir ferred form of embodiment thereof taken in conchamber I4 and the steam discharge nozzle 24.

In the usual operation of the apparatus, sufnection with the attached drawings, in which:

Fig. 1 is a partial elevation with parts in cenficient heat is transferred to the water in the tral vertical section through an improved form chamber l5 to cause a continuous evaporation of of evaporator; a part thereof. I find, however, that the steam Fig. 2 is a partial horizontal cross section taken formed usually contains an objectionable amount substantially along the line 2-2 of Fig. l; of entrained solid matter which may amount Figs. 3 and 4 are vertical cross sections taken to approximately 1% of its total weight. This respectively along the lines 3-3 and 4-4 of Fig. material must be removed, and I, therefore, provide a suitable scrubbing section through which This invention relates to improvements in tioned, the water chamber being adapted to re- 1; and

Fig. 5 is a vertical section of a modified 'form 49 the steam must pass. This scrubbing section inof construction. cludes a relatively horizontal plate or deck 25 suitably perforated and provided with upstand- In accordance with the preferred form of embodiment of my invention, I provide an evaporator for the generation of steam in the production of boiler feed water, in which the maximum efficiency of heat transfer is obtained with a minimum loss of sensible heat. The heat source may be of any type as it is only in indirect heat exchange with the water and the water is of any available type and is usually alkali treated but ing risers 26, through which the steam passes. These risers 26 may carry imperforate caps 21 in the nature of well-known bubble caps, the edges of which are preferably serrated, such caps being spaced sufllciently from the upper ends of the risers 25 so that the steam will pass upwardly through the deck 25, downwardly. under the cap 21, and thence upwardly into the chamis evaporated to provide pure distillate. ber I3. The passage of steam in this direction In detail, the evaporator is generally indiis definitely established by the provision of bafcated at I0. It consists substantially of a horifies 29 and 30. zontal elongated vessel which includes a steam To establish a scrubbing action, the feed wagenerating chamber ll, asteam scrubbing chamter, which is introduced through the pipe IS,

the vapor chambers ll, l2, l3, and I4 above menis carried down by means of the pipe 3i onto the deck 25. As will be seen in Figs. 2 and 3, the pipe Si is provided with a series of openings 32 on the bottom so that the water which is introduced will be discharged substantially across the width of the deck 25. A suitable height of liquid is established on the deck 25 by means of the downilow pipes 33, which extend suiiiciently above the deck 25 so that the water level as shown in Fig. 3 will partially cover the walls of the caps 27, and the steam, which thus passes under the caps 21, must therefore pass through some of the water before it can reach the cham ber i3.

I have found in practice that the passage of steam containing a certain amount oi entrained solids through the water in this manner will accomplish a substitution of moisture for solids with the result that the solids contained in the steam are removed therefrom and tend to flow down the pipes 33 into the water chamber IS.

The steam which reaches the chamber I3 is, therefore, free of solid matter but contains some entrained moisture which is also objectionable, and I, therefore, provide a multiple screen filter 35 which is preferably of a suitable mesh wire which removes the entrained moisture from the steam. The moisture follows the screen into the water chamber 15. The steam, therefore, that reaches the chamber H is substantially free of moisture and solids and is adapted for use;

The evaporator may be provided with suitable blowdown openings 36. Provision maybe made as at 3'! for the insertion of a gauge glass for inspection of the liquid level in the evaporator; provision may also be made at 31a for the installation of a liquid level control device. Connection 38 may be adapted for the insertion of a pressure relief valve or the like. Raw water may be introduced at 38a to be sprayed over the heat exchange bundle I! when it is necessary or desirable to remove the scale therefrom. I also find it desirable to provide the bailie 29 with a channel 39 which is connected with a downpipe 40 extending below the water level in the chamber l as shown in Fig. 3 to draw of! any moisture which may have been knocked out ot the steam in its contact with the baiile 29. This reduces the moisture content of the steam and is beneficial in producing the maximum quality of steam in the chamber ll,

An evaporator of this type is of particular ad vantage where a heating fluid is available which it is undesirable to bring into direct contact with the water in the chamber ii. In many industrial chemical fields heating media are available which are of such poor quality as to be objectionable if passed directly into the water.

The evaporator is also of particular advantage in that there are no moving parts with nothing to become damaged or to get out of order; it is necessary only to maintain the desired level of water which simultaneously covers the heating coll l8 and forms a continuation of the bailies which separate the respective chambers one from the other. The flow of steam is thus automatically controlled by thewater.

It is also possible to provide a vertical type of evaporator, one form 01 which is shown in Fig. 5. In this case the shell 50 is substantially cylindrical and has the water portion 5|, the level of which is maintained such that the heating coil 52 is normally submerged. The heating coil is pref erably provided with a detachable tube sheet 53, as in the first case, and a channel 54 havinga aeoaoea safety valve nozzle 59 interconnects certain of the tubes with the heating media inlet nozzle 55. In the particular construction shown, this is adapted to receive a condensable material such as steam with the condensate removed through the drain 56. It is, of course, to be understood that, if a liquid such as hot oil or other material is used, a second nozzle would be provided for the removal thereof.

The water portion 5| of the evaporator is relatively deep in this form of the invention with a resultant adequate sludge collecting section at the lower portion, and a blowdown 51 is provided for the removal of the sludge as desired. Furthermore, a descaling spray means shown at 58 may be provided so that the scale may be washed from the heating coil 52 as desired.

Above the water chamber 5| I provide a steam evaporating chamber 60, above which is provided a relatively horizontal bubble plate having risers 62, bubble caps 63, and a downpipe 64. This latter will maintain a liquid level on the deck, and the steam must pass through this liquid on its way to the outlet. As in the prior case, the feed water is introduced onto the bubble plate as through the nozzle and a substitution of moisture for the solids in the steam is thereby accomplished.

The steam then rises through the steam drying section 66 and passes through suitable screens 61, which remove the moisture, and the dry and clean steam then discharges through the outlet nozzle 68. A vent may be provided at I9 tor the removal of air, and nozzles may be provided at 10 and H for suitable gauges and relief valves.

If desired, a nozzle 12 may be provided for sampling purposes, and the evaporator wall may also be provided with nozzles, indicated at 13 and H, for the gauge glass and the liquid level control. The device may also be provided with illuminated ports 18 and 11 for purposes of inspection.

While I have shown a preferred form of embodiment of my invention, I am aware that modiflcations may be made thereto, and I, therefore, desire a broad interpretation of my invention within the scope and spirit of the description herein and of the claims appended hereinafter. Iclalm:

1. An evaporator having a shell, 9. heat exchange coil in a lower part of said shell and normally submerged in contained water therein, an evaporation chamber, a steam scrubbing chamber, a steam drying chamber, and a vapor reservoir chamber above the normal water level in said shell, said chambers being interconnected whereby steam formed in said evaporation chamber must flow through each of said chambers in the order named, partition members delimiting said chambers to provide a circuitous path of flow for the steam, one of the partition'members delimiting the scrubbing chamber being a perforated horizontal plate and having bubble caps surmounting the perforations to form steam scrubbing devices, means to introduce feed water above said scrubbing devices whereby the steam must pass through said feed water on said plate and exchange solid matter entrained therein i'or moisture, and vertical moisture removing means forming the partition between the steam drying chamber and the reservoir chamber to remove substantially all or the moisture from the steam in its passage therethrough.

2. An evaporator having a shell, a heat exchange coil in a lower part of said shell and normally submerged in contained water therein, an

evaporation chamber, a steam scrubbing chamher, a steam drying chamber, and a steam reservoir chamber above the normal water level in said shell, partition members delimiting said chambers and extending into said water whereby said water forms one 'of the walls of said chambers, said scrubbing chamber and said evaporating chamber being interconnected so that the steam formed in said evaporating chamber must pass through the scrubbing chamber into the steam drying chamber, scrubbing devices in said scrubbing chamber, means to introduce feed water above said scrubbing devices whereby the' steam must pass through said feed water and exchange solid matter entrained therein for moisture, and moisture removing means forming the partition between the steam drying chamber and the reservoir chamber whereby substantially all of the moisture is removed from the steam in its passage therethrough, said evaporator being a substantially cylindrical horizontal shell with a tapered, truncated, conical portion forming the by said Water forms one of the walls of said chambers, said scrubbing chamber and said evaporating chamber being interconnected so that the steam formed in said evaporating chamber must pass through the scrubbing chamber into the steam drying chamber, scrubbing devices in said scrubbing chamber, means to introduce feed water above said scrubbing devices whereby the steam must pass through said feed water and exchange solid matter entrained therein for moisture, and moisture removing screens forming the partition between the steam drying chamber and the reservoir chamber whereby substantially all oi the moisture is removed from the steam in its passage therethrough, said shell being a substantially tubular member having a horizontal axis, in which bafiies comprise some of the partition members that delimit the respective chambers, said, baffles being vertical and spaced horizontal- 1y with respect to each other whereby the steam is given a circuitous course from its point of formation to its point of discharge.

4. An evaporator consisting of a horizontal shell, a heat exchange coil therein and normally adapted to be surrounded by water contained in said shell, a steam separator in said shell, a steam outlet in said shell, said separator including imperforate steam directing baffles, one of which extends into said water, and a perforate baflie, bubble caps surmounting the perforations in said perforate bail'ie, means to feed water onto. said perforate baiiie above said bubble caps, means to maintain a feed water level above the lower margins of said bubble caps whereby steam formed in said evaporator must pass through the feed water on said perforate baiiie, means to remove the moisture entrained in said steam, said means including a vertical, perforate baffie spaced between the bubble caps and the steam outlet, said vertical baffle extending to a point below the top of the coil whereby the body of water covering said coil willact as a partial baiiie to direct the flow of steam through said vertical bafile, said water also serving as a reservoir for solids contained in said water, and means to remove the solids from the shell.

5. An evaporator consisting of a vertical shell having a water chamber in the lower portion thereof and a steam outlet in an upper part thereof, a heat exchange coil extending into said evaporator and normally submerged in water contained in said water chamber, a steam evaporating chamber above the water chamber, a steam scrubbing chamber having a horizontal perforate baiiie extending across the shell, bubble caps surmounting the perforations in said periorate baflle, means to introduce feed water onto HAROLD M. GRAHAM. 

